Electronic circuitry such as printed circuits found in television receivers, copying machines, and missile guidance systems is often so intricate that the only possible method of cleaning foreign accumulations from such circuits is contacting with a volatile organic solvent until the accumulations are dissolved, removing the circuits from contact with the solvent and allowing the solvent remaining on the circuits to evaporate.
The requirements for such cleaning solvents are stringent. A solvent should be low boiling, non-flammable, non-toxic and should also exhibit a high solvent power for the residues to be removed without attacking the substrate being cleaned. While boiling and flammability characteristics can often be adjusted by preparing mixtures of solvents, these are often unsatisfactory because they fractionate to an undesirable degree during use. Such mixtures also fractionate during recovery, making it difficult to recover a solvent mixture with the original composition.